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Securing CBC mode Against Padding Oracle Attacks Securing CBC mode Against Padding Oracle Attacks

Securing CBC mode Against Padding Oracle Attacks - PDF document

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Securing CBC mode Against Padding Oracle Attacks  \n  \r  \r\n \r     \r  !" Outline  #! $%# &'!()   &*$\n  + &*$\n,\n -  "  $% !)    $ \r  $ \r. \n  /&$&$ )  *0#+   \r"& Cipher-Block-Chaining (CBC) $\r  1  \n +$\r  1    \n #2 3 #2  3  #2 +3 #2  +3  Padding 4$\n&  )\n\n&\n    \n)    $%\n5  6\r  $ $% !) \n&7&*$8 Padding Oracle &*$ 6\r4  , Do padding oracles exist in real life? 9\n \r :  $) &*$\n& )   \n$  $%\n; Side Channel Attacks "  \r\n;$ $  &  )\n ))  $  $\r  ) \n  ,)\n1") )\n\n&\n $ \n; Padding Oracles in Practice"  +$\r  /=)\n\n&\n\n  $;  / . " \n"\n   $ \n\n$ \n. $  \n, $\r  \r; Padding Oracles in Practice4$   \n\n  & \r $ $%    $$\n  " )\n\n&\n\n\n$   $  \n  &\n  Padding Oracles in Practice�"  .\n\n&\n. $\r    \n)\r\n  ). &   )\n\n&\n$\r      $$\n \n\n\n \n   Padding Oracles in Practice�"  7\n\n 4 $  �" 8\r &6\r6& ,\r ?@@A  " & $\n&\r  #\n)       $  , ;  \r#$\r & $   \n )   $  , ;  $ $\n\n \n\n\n     \n\n\n)  $ \n\n\n $\n\n ) ,  $% $ \n\r\n \n);&;\n\n  Padding Oracle Attack #2  +3    \n B   ! \n  & $%  \n  !"" &*$   & $ \n Example: CBC-PAD !#+  !\r #   &\n$ )  4 # \r \nC  \n  $%  # \r \n  #$  #\r \n # # # # %%%%%%$ Example: CBC-PAD   & $ \n   ,   \n 2  ??  AAA  $;  " \n $$   \n1 2�?  2�?2E2�??F ;  " & 2 \n) \n %\r  $$;  \n \n  \n \r    , ;    $ &\n$\n  & $$  ,  \r   ); Solving the Problem &'\r\r(&\n$ )-      \n\n$ )\n\n$-  4\n \n     $ $\r  - Provable Security 4  $\r \n\n.$7 \n $$\r  8;  /\n  )\r$ *G$ 1  \n$ \r  $  \n) \r     \n$ \r  ) &\n;     *  $     * \r&) ; Provable Security,)1  \n\n)  $  $ \n\n  $  ;  $  \n\n$ \r\r&&$    #\r\n\n  ;    %  $ )\n    ; Practice Orientated Provable Security 4  $\r! &\r  4 &  $%$ \n  \n$ \r   $ \n$ \r# )  $  C     \n$ \r Security Models 4\n &\n  \r1     & ' (     )' (  / \n\n'/ (  ) $$ \r')( Relations between Models  # # & # #  ) /# #\n\n ) $ Left-or-Right ,)  # *+,\n *(-!$,$,*((   *( ,)  # *+,\n *(-!$,$,*((';(   *( \n\r. **( #"3JKL**(MNOK  \n\r=\n &   \n\n\r)) $$\r  \n$ ) J', (; Defining CBC Mode/ /, /, / " $\r  $   %\n \n & )    $%\n5;  " $\r  $     \n)\n\n&\n & )    $%\n5; /  / , / , / " $\r  $    %\n)&   $  \n $\r \n;  " $\r  $  )\n  $\r  ; LoR-PO-CPA ,)  #*# *+,\n /*(/ -!$,$,*((';(   *( \n\r. **( #*#JKL**(MNOK  \n\r=\n & $$ \n$ \r) \n\r  $&&;)) \n$$ \n   ) \n)   \n\r; Finding a Secure Padding Method "\n%1  /\n$&)  ) \n$;   !)  \n$  \n&) ; OZ-PAD *#0 '*0(&)   !    &)   /\n  2   ,  " 5  )  @ \n   $%\n  2 @@@@@;;PP;P@@ OZ-PAD   *0#+) \n  , \n$ $ \r;  *,$  1  4 \n  $%  , \n5  $%;  " \n & $ \n$  , ;  " $ $   &\n \n\nC  &\n\n&  , ; OZ-PAD is not LoR-PO-CPA 46  +3 ) 46 )Å)@ +*+ JQ4 *\n JQ6  2 $%)\n\n&\n + R \n  $\r   $ $$%? $%\n $  ,  12""  $ \n $\r     +  \n; One-way Security of OZ-PAD \n\n   6\r=\n $%;  $ &$  , $ \n\r $ \n &$ & , ;       \n \n$   1   \n Arbitrary Tail Padding " \n \n1  \r            ! *  ) 1  ,) \n    ,     \n  \n+++\n\n+\n++%%%%%%%%$\n @@@@@PPPPPP@@ What are the advantages?   \r &\n &\n )\n\n&\n;  &*$\r\n ;  6\r=\n $%\n \n  ; LoR-PO-CPA Security? \n )\n  \n$ \r;     \n\r$ $%!+ \n\r,\n \n  $ $%!;  $  , \n &\n\n $) & $\n ) $ ; !+ !  & )  !' !+') = = ) *+,\n #*# #!+! Defining Good/Bad Padding Schemes  ) *0#+\n &;  7& 8&\n$ )\n   &\n; CCA Security –Authenticated Encryption \n  $ )!) \n )&\n$ )\n ).;    $ $\r   \n$&  ;&; $%   .\r \r\n $ ) \n  $ $\r  $ ); Padding Oracles in Practice�"  .\n\n&\n. $\r    \n)\r\n  ). &   )\n\n&\n$\r      $$\n \n\n\n \n   Padding Oracles in Practice�"  7\n\n 4 $  �" 8\r &6\r6& ,\r ?@@A  " & $\n&\r  #\n)       $  , ;  \r#$\r & $   \n )   $  , ;  $ $\n\n \n\n\n     \n\n\n)  $ \n\n\n $\n\n ) ,  $% $ \n\r\n \n);&;\n\n  CCA Security –Authenticated Encryption \n  $ )!) \n )&\n$ )\n ).;    $ $\r   \n$&  ;&; $%   .\r \r\n $ ) \n  $ $\r  $ ); Summary 4 \n 6\r=\n&*$ $%    $    \n$ \r  4  $S$ \r. \n  4\n$\n\n   $&) \n  *0#+   \r"&  7& 8&\n$ )\n   &\n Thank YouB\n  \n-